Cumulative pre-cooling methods do not enhance cycling performance in tropical climate

perceptions (i.e., thermal environment, RPE) and core temperature of athletes more than only internal pre-cooling with menthol; and (2) whether, in the mixed conditions, adding menthol to the external pre-cooling would improve the cycling performance, perceptions and core temperature. Materials and methods Participants Seven heat-acclimatized (i.e., living and training in Guadeloupe) trained male road cyclists (age: 29±8 years, weight: 67±8 kg, maximal aerobic power: 375±65 watts) were recruited among Guadeloupean cycling teams. They were well-trained and were regularly competing in elite road races. These cyclists were training at least 15 hours per week at the time of the study (weekly training 17±2 hr). All completed a medical screening questionnaire and gave written informed consent prior to the study, which was approved by the Ethics Committee of the Training and Research in Sport Science Unit in Guadeloupe (Ministry of Higher Education and Research) and conducted according to the Declaration of Helsinki. The cyclists were instructed to avoid training sessions for 24 hr prior to testing and were allowed 60 min of light-intensity exercise 48 hr before each experimental session. Caffeine, drugs and alcohol were strictly prohibited for 24 hr before the start of the experimental session. The cyclists were instructed to consume the same meals each day before each session. What- ever the time of passage, the cyclists were asked to have, 2 hours before, the same standardized French breakfast (bread, butter, jam, yogurt) and 500 mL of water at ambient temperature. For

each participant, the sessions began at the same time of day to remove any effect of circadian variation (between 10:00 a.m. and 2:00 p.m.). Procedure Participants performed trials under three randomized experimental conditions of pre-cooling —separated by one week—followed each time by a cycling performance trial on an outdoor velodrome in ecological hot and humid conditions (Guadeloupe, French West Indies; WBGT: 27.7±0.3˚C; relative humidity: 76±2%). The cyclists completed each entire experimental ses- sion on their personal road cycling bike, using standardized equipment (no extension, classic helmet, racing clothing during the cycling performance). The three experimental sessions con- sisted of a standardized warm-up associated with one of the following randomized cooling conditions: (1) ingestion of cold menthol water + wearing a cooling vest soaked in ice water (ICE-VEST), (2) ingestion of cold menthol water + wearing a cooling vest soaked in ice men- thol water (MEN-VEST), and (3) ingestion of cold menthol water without wearing a vest (NO-VEST). The cooling vest covered the entire torso and back. Each experimental session included (1) a 30-min warm-up on a cycle trainer (Tacx Satori T1856 Tacx BV, Wassenaarn, The Netherlands) with pre-cooling strategies, and (2) the cycling performance on the track. The warm-up consisted of a gradual increase in intensity in such a way as to resemble as much as possible the protocols used by the athletes when competing in time trial events: 10-min at

i2, 10-min at i3, 3-min at i4, 2-min at i5 and 5-min at i2 ([35] for intensity chart). A standard- ized transition of 5 min between the end of the warm-up and the beginning of the cycling per- formance test gave the athletes time to dress in their complete outfits, take their bikes out of the home-trainer, and get to the starting line. During the cycling performance, they had no information that could help them manage the pace and were only informed when they had reached the last 5 minutes and the last minute of the 20-minute test. During pre-cooling, taking place during the warm-up, the cyclists ingested a total of 8 g.kg- 1 of cold menthol water (3˚C) divided into three intakes every 15 min at T0, T15 and T30. The PLOS ONE Tropical cycling performance and cumulative pre-cooling PLOS ONE | https://doi.org/10.1371/journal.pone.0291951 October 12, 2023 3 / 15